The correlation between femoral condyle radii and subject height.

In the sagittal plane, the distal femoral condyles can be modeled using anterior and posterior circle segments. The aim of this study was to investigate how the radii of these segments vary with subject height. The MRI scans of 20 male and 20 female knees were analyzed with a computer to extract the radii of each condyle segment. These radii were then correlated with the patient's height. The anteromedial radii ranged from 22.6 to 32.6 mm. The posteromedial radii ranged from 15.4 to 26.3 mm. The anterolateral radii ranged from 19.7 to 30.4 mm. The posterolateral radii ranged from 15.2 to 23.6 mm. The radii had a strong correlation with patient height, with some differences between sexes. Linear regressions of the data yielded equations for estimating condyle radii from height. These radii estimations can be helpful in the clinical assessment of knee movement and treatment outcome.

Magnetic tracking: a novel method of assessing anterior cruciate ligament deficiency.

INTRODUCTION: The Lachman test is commonly performed as part of the routine assessment of patients with suspected anterior cruciate ligament (ACL) deficiency. A major drawback is its reliance on the clinician's subjective judgement of movement. The aim of this study was to quantify Lachman movement using a magnetic tracking device thereby providing a more accurate objective measure of movement. PATIENTS AND METHODS: Ten patients aged 21-51 years were assessed as having unilateral ACL deficiency with conventional clinical tests. These patients were then re-assessed using a Polhemus Fastrak magnetic tracking device. RESULTS: The mean anterior tibial displacement was 5.6 mm (SD = 2.5) for the normal knees and 10.2 mm (SD = 4.2) for the ACL-deficient knees. This gave an 82% increase in anterior tibial displacement for the ACL deficient knees. This was shown to be highly significant with P = 0.005. CONCLUSIONS: The magnetic tracking system offers an objective quantification of displacements during the Lachman test. It is convenient, non-invasive and comfortable for the patient and is, therefore, ideally suited for use as an investigative tool.

Instant center of rotation estimation using the Reuleaux technique and a Lateral Extrapolation technique.

A mathematical model of a rolling wheel was used to investigate the errors encountered when the Reuleaux technique is employed to estimate planar instant centers of rotation (ICRs). The investigation showed that large errors can result when this pole measurement technique is applied to objects rotating more than 12 degrees. The investigation also showed that these errors can be substantially reduced by applying a new Lateral Extrapolation technique to the pole data. When the Reuleaux technique is applied to marks on a 10cm radius wheel, the resulting offset errors from the ICR are 3.96cm for a 45 degrees roll and 1cm for a 12 degrees roll. Following lateral extrapolation, these offset errors reduce to 0.52cm for the 45 degrees roll and less than 0.04cm for the 12 degrees roll. Thus, the extrapolation technique is over seven times more accurate for a 45 degrees roll, and over 25 times more accurate for a 12 degrees roll. The extrapolation technique has been validated with the model for joints that exhibit both slip and roll, such as the knee. As joint ICR pathway measurement can be used to detect pathology, these accuracy improvements offer potential benefits for clinical applications.

Thromboembolic complications after electrical cardioversion in patients with atrial flutter.

PURPOSE: To determine the incidence of thromboembolic complications after cardioversion in patients with atrial flutter. SUBJECTS AND METHODS: We reviewed 615 electrical cardioversions performed electively in 493 patients with atrial flutter. Embolic complications were evaluated during the 30 days after cardioversion. Follow-up data were obtained by follow-up visits and by contacting the treating physician. RESULTS: Anticoagulants had been administered in 415 cardioversions (67%). Cardioversion was successful in 570 procedures (93%). Three embolic events (in 3 patients) occurred in the 30 days after 550 successful cardioversions with completed follow-up (0.6% of successful procedures; 95% confidence interval, 0.1% to 1.6%). Two of the 3 patients had not been anticoagulated, whereas the third patient had subtherapeutic oral anticoagulation. No embolic event occurred in procedures performed with adequate anticoagulation. The incidence of embolism in patients regardless of subtherapeutic anticoagulation was 1% (3 of 303 successful cardioversions). CONCLUSIONS: We observed a low (0.6%) incidence of postcardioversion thromboembolic complications in patients with atrial flutter. Embolic events did not occur in patients with adequate anticoagulation.

Left atrial volume: important risk marker of incident atrial fibrillation in 1655 older men and women.

OBJECTIVE: To evaluate the contribution of left atrial (LA) volume in predicting atrial fibrillation (AF). PATIENTS AND METHODS: In this retrospective cohort study, a random sample of 2200 adults was identified from all Olmsted County, Minnesota, residents who had undergone transthoracic echocardiographic assessment between 1990 and 1998 and were 65 years of age or older at the time of examination, were in sinus rhythm, and had no history of AF or other atrial arrhythmias, stroke, pacemaker, congenital heart disease, or valve surgery. The LA volume was measured off-line by using a biplane area-length method. Clinical characteristics and the outcome event of incident AF were determined by retrospective review of medical records. Echocardiographic data were retrieved from the laboratory database. From this cohort, 1655 patients in whom LA size data were available were followed from baseline echocardiogram until development of AF or death. The clinical and echocardiographic associations of AF, especially with respect to the role of LA volume in predicting AF, were determined. RESULTS: A total of 666 men and 989 women, mean +/- SD age of 75.2 +/- 7.3 years (range, 65-105 years), were followed for a mean +/- SD of 3.97 +/- 2.75 years (range, < 1.00-10.78 years); 189 (11.4%) developed AF. Cox model 5-year cumulative risks of AF by quartiles of LA volume were 3%, 12%, 15%, and 26%, respectively. With Cox proportional hazards multivariate models, logarithmic LA volume was an independent predictor of AF, incremental to clinical risk factors. After adjusting for age, sex, valvular heart disease, and hypertension, a 30% larger LA volume was associated with a 43% greater risk of AF, incremental to history of congestive heart failure (hazard ratio [HR], 1.887; 95% confidence interval [CI], 1.230-2.895; P = .004), myocardial infarction (HR, 1.751; 95% CI, 1.189-2.577; P = .004), and diabetes (HR, 1.734; 95% CI, 1.066-2.819; P = .03). Left atrial volume remained incremental to combined clinical risk factors and M-mode LA dimension for prediction of AF (P < .001). CONCLUSION: This study showed that a larger LA volume was associated with a higher risk of AF in older patients. The predictive value of LA volume was incremental to that of clinical risk profile and conventional M-mode LA dimension.

A surface-marker imaging system to measure a moving knee's rotational axis pathway in the sagittal plane.

This paper describes a new surface-marker imaging system designed to measure the rotational axis pathway (RAP) of a moving knee in the sagittal plane. Measurement of this parameter can provide important information about a knee's slipping and rolling action that can aid clinical assessment. Seated subjects are video recorded as they actively extend their legs. A series of stills is then captured and analyzed to extract the coordinates of markers placed on the subjects upper and lower legs. These coordinates are then processed to deduce an instant center of rotation (ICR) for each still. These ICRs are then plotted to derive the joint's RAP. The system has been validated with a mechanical model and tested in a clinical study of ten patients with unilateral anterior cruciate ligament (ACL) ruptures. The study found that the system could consistently measure differences between a patients normal and injured knees. Leg extension caused the normal knees ICRs to displace anteriorly with a mean value of 17.4 mm, whereas the injured knees had a mean displacement of 7.5 mm. This loss of roll in the ACL-deficient knees is consistent with their abnormal biomechanical arrangement.

Personal ultrasound imager: abdominal aortic aneurysm screening.

BACKGROUND: Miniaturized ultrasonographic machines (2.5-MHz curved-array transducer connected to a compact 2.6-kg console), termed personal ultrasound imagers (PUIs), may enable detection of occult abdominal aortic aneurysms (AAAs). OBJECTIVES: Our goals were to determine whether a PUI is capable of screening for AAAs and to compare the results with an established screening examination with standard echocardiography (SE). METHODS: One hundred twenty-five patients (aged >70 years) with hypertension who were referred for transthoracic echocardiography were enrolled. After SE, a focused screening with a PUI examination was performed by a blinded sonographer. An AAA was defined as a focal enlargement of the aorta >30 mm. Results and the length of time to image the aorta were compared for both tests. RESULTS: We studied 64 men and 61 women (aged 76.8 +/- 5 years; mean blood pressures: systolic 145.7 +/- 18 and diastolic 78.6 +/- 10; body surface area 1.9 +/- 0.2 m(2)). The mean time for SE was 2.9 +/- 1.5 minutes and for the PUI examination was 4.6 +/- 2.3 minutes. By using SE as the gold standard, the sensitivity and specificity of the PUI were 91% and 96%, respectively. The positive predictive value of the PUI was 71%, and the negative predictive value was 99%. CONCLUSION: A PUI can be used to screen for occult AAAs as an extension of the physical examination. Results are comparable to an established screening strategy that uses more expensive, nonportable echocardiographic equipment.

Shortness of breath secondary to a pet cockatiel.

A case of hypersensitivity pneumonitis in a 40-year-old patient secondary to a pet bird is presented. The clinical presentation, diagnosis, and management of hypersensitivity pneumonitis are reviewed.